1. Field of the Invention
The invention generally relates to congestion control techniques, and more particularly, to methods for congestion control for Machine Type Communication (MTC) devices or low priority devices, and apparatuses using the same.
2. Description of the Related Art
For a long time, various machines have been provided to make our lives more convenient in every way. Generally, machines, nowadays, are equipped with computing processors and software to accommodate us with more intelligence-based services. With the advancement of wireless communications, Machine Type Communication (MTC) has been developed to enable communications between remote machines for exchanging information and operating without human interaction. Especially for critical public infrastructures, such as water treatment facilities or bridges, MTC sensors may be employed to monitor the operation statuses of facilities and report measurement results back to control centers via wireless communication networks, such as the Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, LTE-Advanced technology, and others.
Take the LTE technology in compliance with the 3GPP TS 23.060 specification, v10.1.0 (referred to herein as the TS 23.060 specification) and the 3GPP TS 25.331 specification, v10.1.0 (referred to herein as the TS 25.331 specification) as an example. When too many mobile devices access the Serving GPRS Support Node (SGSN), congestion may occur in the SGSN, i.e., the Packet-Switched (PS) domain of the service network is congested. For the PS domain congestion, the SGSN may instruct Radio Network Controller/Base Station Subsystem (RNC/BSS) to reject the connection request for the PS domain from any of the MTC devices or low priority devices, wherein an extended wait timer is indicated along with the rejection of the connection request. When the connection request is rejected, the MTC device or low priority device starts the extended wait timer and does not initiate establishment of a PS connection during the running period of the extended wait timer. However, there are situations where an MTC device or low priority device may transmit a connection request for both the PS domain and the Circuit-Switched (CS) domain for initiation of a combined attached procedure or combined routing area update procedure when the PS domain congestion occurs. Although the CS domain of the service network may not be congested, the behavior of the service network for the CS domain is indeterminate for such cases. As a result, problems such as indeterminate behaviors of the service network and the MTC device or low priority device may occur.